Improving Dust Control at Transfer Points with Settling Zone Adjustments
The settling zone refers to the space enclosed by a covered skirtboard at a transfer point, sometimes including an additional enclosed volume of the load zone after the product has been placed onto the belt. This expanded section of the skirtboard, which constitutes the settling zone, allows the air moving through the transfer point to decelerate, facilitating the settling of dust rather than its escape.
The size of the settling zone depends on six factors: the width and speed of the belt, chute width, amount of airflow, depth of the material bed, and the diameter of the largest lump of material that may pass through the settling zone.
An increase in any of these factors necessitates a corresponding enlargement of the settling zone. Calculations to determine the size of a settling zone are focused on the airspace only – the area above the cargo. Measurements of the cross-sectional area of the chute exit should exclude the area occupied by the material.
To further slow down the air in the settling zone, another method is to install rubber curtains as baffles. It is also crucial to ensure that any holes in the transfer point are sealed, whether they result from rust, wear, or an opened door.